Void plugs and expanding seals for gate valves

Abstract

A gate valve comprises a first bore having a first seat pocket and a second bore having a second seat pocket. First and second valve seats are configured to be positioned in the first and second seat pockets, respectively. A gate of the gate valve comprises a first side for sealingly engaging with an inner surface of the first valve seat and a second side for sealingly engaging with an inner surface of the second valve seat. The gate is moveable between an open position and a closed position. First and second valve seats comprise biasing mechanisms for providing a sealing force between the inner surface of the valve seats and the gate. The gate valve may further comprise void plugs for reducing space within the internal cavity of the valve. Shims may be used to decrease the clearance at the gate to seat sealing surfaces.

1 . A valve seat comprising:
 an inner surface for sealingly engaging with a gate of a valve;   an outer surface opposite the inner surface; and   a biasing mechanism;   wherein, the valve seat is configured to be positioned in a seat pocket of the valve and wherein, in operation, the biasing mechanism biases the valve seat towards the gate for providing a sealing force between the inner surface of the valve seat and the gate.   
     
     
         2 . The valve seat of  claim 1  wherein the biasing mechanism comprises:
 an annular groove in the outer surface of the valve seat; 
 a resilient ring configured to be positioned in the annular groove; and 
 a rigid ring configured to be positioned on top of the resilient ring in the annular groove; 
 wherein, in operation, compression of the resilient ring forces the rigid ring towards a shoulder of the seat pocket thereby biasing the valve seat towards the gate. 
 
     
     
         3 . The valve seat of  claim 2 , wherein the resilient ring comprises an elastomer. 
     
     
         4 . The valve seat of  claim 2 , wherein the rigid ring comprises a metal. 
     
     
         5 . The valve seat of  claim 2 , wherein the rigid ring comprises at least one vent for relieving pressure in the annular groove. 
     
     
         6 . A gate valve comprising:
 a first bore comprising a first seat pocket and a second bore comprising a second seat pocket, the first and second seat pockets each comprising a respective shoulder;   a first valve seat positioned in the first seat pocket and a second valve seat positioned in the second seat pocket, the first and second valve seats each comprising a respective inner surface and a respective outer surface opposite the respective inner surface;   a gate comprising a first side for sealingly engaging with the inner surface of the first valve seat and a second side for sealingly engaging with the inner surface of the second valve seat, the gate moveable between:
 an open position, wherein the first bore and second bore are fluidly connected for allowing fluid flow therebetween; and 
 a closed position, wherein the gate substantially prevents fluid flow between the first bore and the second bore; 
   wherein, the first valve seat further comprises a biasing mechanism for biasing the first valve seat towards the gate and for providing a sealing force between the inner surface of the first valve seat and the first side of the gate.   
     
     
         7 . The gate valve of  claim 6  further comprising at least one shim positioned between the first valve seat and the shoulder of the first seat pocket. 
     
     
         8 . The gate valve of  claim 7 , wherein the at least one shim comprises a rigid plastic, Teflon®, brass, bronze, Nylatron®, steel, or stainless steel. 
     
     
         9 . The gate valve of  claim 6  further comprising:
 an internal cavity for accepting a lubricant; and 
 one or more void plugs configured to occupy a respective volume in the internal cavity, the one or more void plugs for reducing the amount of the lubricant that can be accepted by the internal cavity. 
 
     
     
         10 . The gate valve of  claim 9 , wherein the one or more void plugs comprise composite material, rubber, or steel, and an overlay of Teflon®. 
     
     
         11 . The gate valve of  claim 9 , wherein at least one of the one or more void plugs is configured to increase the flow rate of the lubricant at the first and second sides of the gate during purging operations. 
     
     
         12 . A void plug configured to occupy a volume in an internal cavity of a valve for reducing the amount of a lubricant that can be accepted therein. 
     
     
         13 . The void plug of  claim 12  further comprising a composite material, rubber, or steel, and an overlay of Teflon®. 
     
     
         14 . The void plug of  claim 12 , further configured to increase the flow rate of the lubricant between one or more clearances in the internal cavity of the valve during purging operations. 
     
     
         15 . A gate valve comprising:
 a first bore comprising a first seat pocket and a second bore comprising a second seat pocket, the first and second seat pockets each comprising a respective shoulder;   a first valve seat positioned in the first seat pocket and a second valve seat positioned in the second seat pocket, the first and second valve seats each comprising a respective inner surface and a respective outer surface opposite the respective inner surface;   a gate comprising a first side for sealingly engaging with the inner surface of the first valve seat and a second side for sealingly engaging with the inner surface of the second valve seat, the gate moveable between:
 an open position, wherein the first bore and second bore are fluidly connected for allowing fluid flow therebetween; and 
 a closed position, wherein the gate substantially prevents fluid flow between the first bore and the second bore; 
   an internal cavity for accepting a lubricant; and   one or more void plugs configured to occupy a respective volume in the internal cavity for reducing the amount of the lubricant that can be accepted therein.   
     
     
         16 . The gate valve of  claim 15 , wherein at least one of the one or more void plugs comprises a flared end for directing the lubricant, during purging operations, between at least one of:
 the first side of the gate and the inner surface of the first valve seat; and   the second side of the gate and the inner surface of the second valve seat.   
     
     
         17 . The gate valve of  claim 15 , wherein at least one of the one or more void plugs are restrained in the internal cavity with one or more restraints. 
     
     
         18 . The gate valve of  claim 15 , wherein the first valve seat further comprises a biasing mechanism for biasing the first valve seat towards the gate and for providing a sealing force between the inner surface of the first valve seat and the first side of the gate. 
     
     
         19 . The gate valve of  claim 15 , further comprising at least one shim positioned between the first valve seat and the shoulder of the first seat pocket. 
     
     
         20 . The gate valve of  claim 19 , wherein the at least one shim comprises a rigid plastic, Teflon®, brass, bronze, Nylatron®, steel, or stainless steel.